<template>
  <div class="shopcart">
    <div class="content">
      <div class="content-left">
        <div class="logo-wrapper">
          <div class="logo" :class="{'highlight':totalCount>0}">
            <i class="icon-shopping_cart" :class="{'highlight':totalCount>0}"></i>
          </div>
          <div class="num" v-show="totalCount>0">{{totalCount}}</div>
        </div>
        <div class="price" :class="{'highlight':totalPrice>0}">￥{{totalPrice}}</div>
        <div class="desc">另需配送费￥{{minPrice}}元</div>
      </div>
      <div class="content-right">
        <div class="pay" :class="payClass">
          {{payDesc}}
        </div>
      </div>
    </div>
    <div class="ball-container">
      <div v-for="(item,key) in balls" :key="key">
        <transition name='drop' @before-enter="beforeDrop" @enter="dropping" @after-enter="afterDrop">
          <div class="ball" v-show="item.show" ><div class="inner inner-hook"></div></div>
        </transition>
      </div>
    </div>
  </div>
</template>

<script>
export default {
  props: {
    deliveryPrice: {
      type: Number,
      default: 0
    },
    minPrice: {
      type: Number,
      default: 0
    },
    selectFoods: {
      type: Array,
      default() {
        return [
          {
            count: 1,
            price: 10
          }
        ]
      }
    }
  },
  data() {
    return {
      balls: [
        { show: false },
        { show: false },
        { show: false },
        { show: false },
        { show: false }
      ],
      dropBalls: []
    }
  },
  computed: {
    totalPrice() {
      let total = 0
      this.selectFoods.forEach(item => {
        total += item.price * item.count
      })
      return total
    },
    totalCount() {
      let count = 0
      this.selectFoods.forEach(item => {
        count += item.count
      })
      return count
    },
    payDesc() {
      if (this.totalPrice === 0) {
        return '￥' + this.minPrice + '元起送'
      } else if (this.totalPrice < this.minPrice) {
        return '还差' + (this.minPrice - this.totalPrice) + '元起送'
      } else {
        return '去结算'
      }
    },
    payClass() {
      return this.totalPrice < this.minPrice ? 'not-enough' : 'enough'
    }
  },
  methods: {
    drop(el) {
      for (let i = 0; i < this.balls.length; i++) {
        let ball = this.balls[i]
        if (!ball.show) {
          ball.show = true
          ball.el = el
          this.dropBalls.push(ball)
          return
        }
      }
    },
    beforeDrop(el) {
      let count = this.balls.length
      while (count--) {
        let ball = this.balls[count]
        if (ball.show) {
          let rect = ball.el.getBoundingClientRect()
          let x = rect.left - 32
          let y = -(window.innerHeight - rect.top - 22)
          el.style.display = ''
          el.style.webkitTransform = `translate3d(0,${y}px,0)`
          el.style.transform = `translate3d(0,${y},0)`
          let inner = el.getElementsByClassName('inner-hook')[0]
          inner.style.webkitTransform = `translate3d(${x}px,0,0)`
          inner.style.transform = `translate3d(${x}px,0,0)`
        }
      }
    },
    dropping(el, done) {
      /* eslint-disable no-unused-vars */
      let rf = el.offsetHeight // 获取dom元素的某些属性就可以触发浏览器重绘
      this.$nextTick(() => {
        el.style.webkitTransform = 'translate3d(0,0,0)'
        el.style.transform = 'translate3d(0,0,0)'
        let inner = el.getElementsByClassName('inner-hook')[0]
        inner.style.webkitTransform = 'translate3d(0,0,0)'
        inner.style.transform = 'translate3d(0,0,0)'
        el.addEventListener('transitionend', done) // transitionend 事件在 CSS 完成过渡后触发 在enter 和 leave中必须使用done进行回调。否则，它们将被同步调用，过渡会立即完成。
      })
    },
    afterDrop(el) {
      let ball = this.dropBalls.shift()
      if (ball) {
        ball.show = false
        el.style.display = 'none'
      }
    }
  }
}
</script>

<style lang='stylus'>
  .shopcart
    position fixed
    z-index 50
    left 0
    bottom 0
    width 100%
    height 48px
    .content
      display flex
      background #141d27
      font-size 0
      color rgba(255,255,255,.4)
      .content-left
        flex 1
        .logo-wrapper
          position relative
          top -10px
          display inline-block
          vertical-align top
          margin 0 12px
          padding 6px
          width 56px
          height 56px
          box-sizing border-box
          border-radius 50%
          background #141d27
          .logo
            width 100%
            height 100%
            border-radius 50%
            background #2b343c
            text-align center
            &.highlight
              background rgb(0,160,220)
            .icon-shopping_cart
              line-height 44px
              font-size 24px
              color #80858a
              &.highlight
                color #ffffff
          .num
            position absolute
            top 0
            right 0
            width 24px
            height 16px
            line-height 16px
            text-align center
            border-radius 16px
            font-size 9px
            font-weight 700
            color #ffffff
            background rgb(240,20,20)
            box-shadow 0 4px 8px 0 rgba(0,0,0,.4)
        .price
          display inline-block
          vertical-align top
          line-height 24px
          margin-top 12px
          padding-right 12px
          box-sizing border-box
          border-right 1px solid rgba(255,255,255,.1)
          font-size 16px
          font-weight 700
          &.highlight
            color #ffffff
        .desc
          display inline-block
          vertical-align top
          margin 12px 0 0 12px
          line-height 24px
          font-size 10px
      .content-right
        flex 0 0 105
        width 105px
        .pay
          height 48px
          line-height 48px
          text-align center
          font-size 12px
          font-weight 700
          &.not-enough
            background #2b333b
          &.enough
            background #00b43c
            color #ffffff
    .ball-container
      .ball
        position fixed
        left 32px
        bottom 22px
        z-index 200
        transition: all 0.4s cubic-bezier(.34,-0.35,.89,.19)
        .inner
          width 16px
          height 16px
          border-radius 50%
          background rgb(0,160,220)
          transition: all 0.4s linear
</style>
